JP6497109B2 - Fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to a fuel cell and a method for manufacturing the fuel cell.

  As described in Patent Documents 1 and 2, for example, conventional fuel cells include a membrane electrode assembly, a resin frame disposed on the outer periphery of the membrane electrode assembly, a membrane electrode assembly, and a resin frame. A pair of separators disposed on both sides of the.

JP 2010-198818 A JP 2008-235159 A JP 2012-195311 A JP 2005-174714 A International Publication WO2010 / 61711 JP 2012-84468 A

  When manufacturing the conventional fuel cell, a resin frame is disposed on the outer peripheral portion of the membrane electrode assembly via an adhesive layer, and the end of the unit is gripped by the hand portion of the transfer robot. It is common to carry and heat press. Since the thickness of the hot-pressed portion is reduced in the pressing direction, the gripped end portion is not hot-pressed and becomes thicker than the hot-pressed central side. When a fuel cell stack is manufactured by stacking a plurality of such fuel cells and pressurizing them in the stacking direction, the manufactured fuel cell stack is loaded only at the ends of the fuel cells that are thicker than the center side. As a result, there was a problem that a seal failure occurred on the center side.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms. According to one aspect of the present invention, a fuel battery cell is provided. The fuel battery cell includes a power generation body having a membrane electrode assembly and a pair of gas diffusion layers disposed on both surfaces of the membrane electrode assembly, and the power generation body in a planar direction along the surface of the power generation body. A pressed fuel cell comprising: a resin frame disposed on an outer periphery of the battery; and a pair of separators disposed on both sides of the power generator and the resin frame, wherein the resin frame has a thickness of approximately A constant flat part and a thin part whose thickness is thinner than the flat part, the thin part being located in a predetermined range including at least a part of the outer periphery of the resin frame in the planar direction, The separator is in close contact with the thin portion.

(1) One form of this invention is a planar direction along the surface of the said power generation body which has a membrane electrode assembly and a pair of gas diffusion layer arrange | positioned on both surfaces of the said membrane electrode assembly, and the said power generation body A fuel cell comprising: a resin frame disposed on an outer peripheral portion of the power generation body; and a pair of separators disposed on both sides of the power generation body and the resin frame. In the fuel cell, the resin frame includes a flat portion having a substantially constant thickness and a thin portion having a thickness that is thinner than the flat portion, and the thin portion is an outer periphery of the resin frame in the planar direction. The pair of separators may be in close contact with the thin portion. According to the fuel cell of this embodiment, the predetermined range including at least a part of the outer periphery of the resin frame is a thin portion having a small thickness, and the thin portion is in close contact with the pair of separators. The thickness of the portion where the predetermined range and the separator overlap does not increase compared to the center side of the fuel cell. Therefore, in a fuel cell stack in which a plurality of fuel cells are stacked, a load is not applied only to a portion where at least the predetermined range and the separator overlap each other, and it is possible to suppress a seal failure from occurring at the center of each fuel cell. .

(2) In the fuel cell of the above aspect, a portion where the separator is in close contact with the thin portion may be a gripping portion for conveyance. According to this fuel battery cell, it is possible to further suppress a sealing failure on the center side of the fuel battery cell.

(3) Another embodiment of the present invention is a method for manufacturing a fuel cell. The fuel cell manufacturing method includes a step of preparing a membrane electrode assembly and a power generation body having a pair of gas diffusion layers disposed on both surfaces of the membrane electrode assembly, a separator, and a resin frame, A step of disposing a resin frame on an outer peripheral portion of the power generation body in a planar direction along a surface of the power generation body, and disposing the separator on a surface of the power generation body and the resin frame; and the disposed power generation body A step of gripping and transporting the resin frame and the separator, and a step of pressing the power generator, the resin frame and the separator in the gripped state. When preparing the resin frame, a resin frame in which a portion corresponding to the predetermined portion to be gripped is thinner than other portions may be prepared, and the thin portion may be in close contact with the separator. According to the method for manufacturing a fuel cell of this embodiment, the same effect as that of the fuel cell of the above embodiment is achieved, and in a fuel cell stack in which a plurality of manufactured fuel cells are stacked, a seal failure is caused at the center of each fuel cell. Will not occur.

  The present invention can be realized in various forms other than the fuel cell and the method for manufacturing the fuel cell. For example, it can be realized in the form of a fuel cell stack in which a plurality of fuel battery cells are stacked, a fuel cell manufacturing method including each step in the fuel cell manufacturing method, or the like.

It is a principal part end view of the fuel cell as one embodiment of the present invention. It is explanatory drawing which shows the outline of the planar structure of a fuel cell. FIG. 3 is an end view taken along line B-B in FIG. 2. It is process drawing which shows the manufacturing method of a fuel cell. It is explanatory drawing which shows the mode of the heating pressurization using a heating press machine. It is a principal part end view of a fuel cell stack. It is explanatory drawing which shows the mode of the heating pressurization using the heat press machine of a reference example. FIG. 10 is an end view of a main part of a fuel battery cell according to Modification 3.

Next, an embodiment of the present invention will be described.
A. Fuel cell configuration:
FIG. 1 is an end view of a main part of a fuel cell as one embodiment of the present invention. As illustrated, the fuel cell 100 includes a membrane electrode gas diffusion layer assembly (hereinafter referred to as “MEGA”) 10 that is a power generation body, separators 20 and 30 that sandwich the MEGA 10, and separators 20 and 30. And a resin frame 40 disposed on the outer peripheral portion of the periphery of the MEGA 10. MEGA is an abbreviation for “Membrane Electrode Gas diffusion layer Assembly”.

  The MEGA 10 includes an electrolyte membrane (electrolyte layer) 12, and a catalyst electrode layer (anode) 14 and a gas diffusion layer 15 are formed in this order on one surface of the electrolyte membrane 12. A catalyst electrode layer (cathode) 16 and a gas diffusion layer 17 are formed in this order on the other surface of the electrolyte membrane 12. As the electrolyte membrane 12, a membrane formed of a solid polymer material such as a fluorine resin, for example, Nafion (registered trademark) can be used. As the catalyst electrode layers 14 and 16, a catalyst layer in which a catalyst such as platinum is supported on carbon particles can be used. The gas diffusion layers 15 and 17 are made of a material having gas permeability and conductivity such as carbon cloth or carbon paper.

  The separator 20 is laminated on the surface of the anode side gas diffusion layer 15 in the MEGA 10. In the separator 20, a fuel gas flow path 22 for flowing hydrogen as a fuel gas is formed along the surface of the anode side gas diffusion layer 15 on the contact surface of the MEGA 10 with the anode side gas diffusion layer 15. . The separator 30 is laminated on the surface of the cathode side gas diffusion layer 17 in the MEGA 10. In the separator 30, an oxidant gas flow path 32 for flowing air as an oxidant gas along the surface of the cathode side gas diffusion layer 17 is formed on the contact surface of the MEGA 10 with the cathode side gas diffusion layer 17. ing. In the present embodiment, metal plates are used as the separators 20 and 30. As the separators 20 and 30, other members having gas impermeability and conductivity may be used. A gasket 60 is formed on the surface of the separator 30 opposite to the resin frame 40. As a material of the gasket 60, rubber or thermoplastic elastomer can be used.

  In the following description, as shown in the drawings, the stacking direction of the separators 20 and 30 with respect to the MEGA 10 (vertical direction in FIG. 1) is referred to as the Z direction, and the direction perpendicular to the stacking direction, that is, the surface direction of the fuel cell 100 Is called the XY plane direction.

  The resin frame 40 has a plate shape and is disposed between the separator 20 and the separator 30. A central portion of the resin frame 40 in the XY plane direction is hollowed out, and the MEGA 10 is disposed in the hollowed portion. That is, the resin frame 40 is disposed on the outer portion (that is, the outer peripheral portion) of the peripheral edge of the MEGA 10 in the XY plane direction. The MEGA 10 has a shape in which the electrolyte membrane 12, the anode-side catalyst electrode layer 14 and the gas diffusion layer 15 are exposed outside the cathode-side catalyst electrode layer 16 and the gas diffusion layer 17 in the XY plane direction. The resin frame 40 supports the exposed portion of the electrolyte membrane 12. The resin frame 40 is made of a thermosetting resin such as epoxy, nylon, or phenol, or a thermoplastic resin such as polypropylene or polyethylene.

  Adhesive layers 50 and 52 are bonded between the resin frame 40 and the separators 20 and 30 and between the resin frame 40 and the exposed portion of the electrolyte membrane 12. As the adhesive layers 50 and 52, a thermoplastic adhesive resin imparted with adhesiveness, for example, a modified polyolefin such as polypropylene or polyethylene into which a silane coupling agent is blended or a polar group such as carboxylic acid is introduced is used. Can do.

  FIG. 2 is an explanatory diagram showing an outline of a planar configuration of the fuel battery cell 100. In the drawing, a plan view of one separator 20 (or 30) is shown. In the drawing, the gasket 60 (FIG. 1) is omitted. As shown in the figure, the fuel cell 100 has a rectangular outer shape, and a portion surrounded by a two-dot chain line in the drawing is a region 10A where the MEGA 10 is present. An oxidizing gas channel 32 (FIG. 1) is formed in this region 10A. A fuel gas flow path 22 is formed on the back surface.

  Six through holes 71 to 76 are formed near the outer edge of the fuel cell 100 in the XY plane direction. The through holes 71 to 76 each constitute a supply or discharge manifold through which the fuel gas, the oxidant gas, and the cooling medium flow by stacking the plurality of fuel cells 100. The fuel gas through holes 71 and 72 are connected to the fuel gas flow path 22 (FIG. 1) via a distribution path (not shown), and the oxidant gas through holes 73 and 74 are connected to the oxidant via a distribution path (not shown). The cooling medium through holes 75 and 76 are connected to the cooling medium flow path 78 (FIG. 1) through a distribution path (not shown). FIG. 1 described above corresponds to a cross-sectional view taken along line AA in FIG.

  3 is a cross-sectional view taken along line BB in FIG. The portion shown in FIG. 3 corresponds to one of four corners (four corners) in the XY plane direction of the fuel battery cell 100, and is an outer portion of the MEGA 10 in the XY plane direction, where the MEGA 10 does not exist. As shown in the figure, separators 20 and 30 are laminated on both sides of the resin frame 40 (outer side in the Z direction) around the four corners of the fuel cell 100.

  The resin frame 40 includes a flat part 42 having a constant thickness t1 in the Z-axis direction and a thin part 44 having a thickness t2 in the Z-axis direction smaller than the thickness t1 of the flat part 42. The thin portion 44 is located in a predetermined range W including at least a part WO of the outer periphery of the resin frame 40 in the XY plane direction, and corresponds to the four corner portions in the present embodiment. The flat portion 42 is a portion excluding the thin portion 44 in the XY plane direction of the resin frame 40. In the present embodiment, the flat portion 42 is a portion on the center side of the resin frame 40 in the XY plane direction and a portion excluding the four corners of the outer periphery. is there. The thickness t1 of the flat part 42 is 1 [mm], for example, and the thickness t2 of the thin part 44 is 0.5 [mm], for example. For this reason, the difference Δt (= t1−t2) between the thickness t1 and the thickness t2 is 0.5 [mm]. The predetermined range W is a portion that is not pressed in the manufacturing process.

  The resin frame 40 and the separators 20 and 30 are bonded to each other by an adhesive layer 50, so that the separators 20 and 30 are disposed on both sides of the resin frame 40 in the Z direction around the four corners of the fuel cell 100. Close to. In the present embodiment, the adhesive layer 50 between the separators 20 and 30 and the flat portion 42 of the resin frame 40 exhibits adhesiveness by a heat press described later, but the thin walls of the separators 20 and 30 and the resin frame 40 are thin. The adhesive layer 50 between the portions 44 is in a state where it is not subjected to hot pressing and exhibits no adhesiveness. Adhesiveness by the adhesive layer 50 is not imparted between the separators 20 and 30 and the thin portion 44, but is in a close state. The conveyance gripping portion 80 is configured by the thin portion 44 and the portions of the separators 20 and 30 that are in close contact with both surfaces of the thin portion 44. That is, these portions function as a conveyance grip 80 when the fuel cell 100 is conveyed in the manufacturing process.

B. Manufacturing method of fuel cell:
FIG. 4 is a process diagram showing a method for manufacturing the fuel battery cell 100. As shown in the drawing, first, the MEGA 10, the separators 20 and 30, and the resin frame 40 are prepared (step 1). Next, the prepared MEGA 10, the separators 20 and 30, and the resin frame 40 are stacked (step 2). Specifically, the MEGA 10, the separators 20 and 30, and the resin frame 40 are stacked so as to have the positional relationship shown in FIG. As shown in FIG. 1, the aforementioned adhesive layer 52 is interposed between the MEGA 10 and the resin frame 40, and the aforementioned adhesive layer 52 is interposed between the separators 20, 30 and the resin frame 40. Then, the lamination is performed.

  Next, the laminate obtained in step 2 is conveyed to the position of a hot press machine described later (step 3). This transfer is performed by a transfer robot having a multi-finger hand unit. The transport robot grips the transport grip 80 with the multi-finger hand and transports the laminate to the heating press.

  Subsequently, by operating a hot press machine to heat and pressurize the laminate, the adhesive layers 50 and 52 are melted, and between the MEGA 10 and the resin frame 40 and between the separators 20 and 30 and the resin frame. 40 is joined (step 4).

  FIG. 5 is an explanatory view showing a state of heating and pressurization using a heating press. As shown in the drawing, the heating press machine HP includes a heating press lower plate HP1 arranged on the lower side in the Z direction and a heating press upper plate HP2 arranged on the upper side in the Z direction. The laminate 90 obtained in step 2 is disposed between the hot press lower plate HP1 and the hot press upper plate HP2. The laminate 90 shown in FIG. 5 corresponds to the four corners shown in FIG. 3, and the transport grip 80 is gripped by the multi-finger hand HA. The laminate 90 is heated and pressurized by the heating press machine HP while being held by the multi-finger hand HA. Specifically, the heating press lower plate HP1 and the heating press upper plate HP2 are flat plates with four corners cut in the plane direction, and heat the portion excluding the conveyance gripping portion 80 gripped by the multi-finger hand portion HA. And pressurizing in the Z-axis direction. That is, the conveyance grip 80 is not heated or pressurized. In other words, the conveyance gripping portion 80, that is, the portion where the separators 20 and 30 are in close contact with the thin portion 44 of the resin frame 40 is not pressed. The reason why the laminate 90 is held by the multi-fingered hand HA and heated and pressurized in this state is to reduce the heat capacity during heating and shorten the heating time.

  Returning to FIG. 4, after the execution of the step 4, the production of the fuel cell ends. A plurality of fuel cells manufactured as described above are then stacked to form a fuel cell stack.

  FIG. 6 is a cross-sectional view of a main part of the fuel cell stack. As illustrated, the fuel cell stack 200 has a structure in which a plurality of fuel cells 100 are stacked. The fuel cell 100 is manufactured by the fuel cell manufacturing method described above. A pair of end plates (not shown) are disposed at both ends of the fuel cell stack 200, and are fastened using fastening members (not shown), thereby stacking the fuel cells 100 in the stacking direction ( A load is applied in the Z direction).

C. Effects of the embodiment:
According to the fuel battery cell 100 configured as described above, the predetermined range W (FIG. 3) including a part W0 of the outer periphery at the four corners of the resin frame 40 is the thin portion 44 having a small thickness. Since 44 is in close contact with the pair of separators 20, 30, the portion where the predetermined range W and the separator overlap does not increase in thickness compared to the center side of the fuel cell 100. Therefore, in the fuel cell stack 200 in which a plurality of fuel cells 100 are stacked, it is possible to suppress the occurrence of a seal failure on the center side of each fuel cell.

  FIG. 7 is an explanatory view showing a state of heating and pressurization using the heat press machine of the reference example. FIG. 7A shows a state before heating and pressurization, and FIG. 7B shows a state after heating and pressurization. In the laminate of this reference example, a pair of separators 920 and 930 are arranged on both sides of the resin frame 940 via an adhesive layer 950, and the thickness t11 of the resin frame 940 is constant. In the state where the four corners of the resin frame 940 are gripped by the multi-fingered hand portion HA, heating and pressurization are performed by the heating press lower plate HP1 and the heating press upper plate HP2.

  Since the vicinity of the four corners of the resin frame 94 is held by the multi-finger hand portion HA, it is not heated or pressurized. For this reason, in the laminate after heating and pressurizing, as shown in FIG. 7B, the thickness t22 (= t11) near the four corners of the resin frame 94 is the other part (center of heating and pressurization). It is larger than the thickness t21 of the side portion and the portion excluding the four corners of the outer periphery). When stacking a plurality of fuel cells manufactured through this hot press process and applying a load, the vicinity of the four corners of the fuel cell is the thickest part. Become. For this reason, in the fuel cell stack of the reference example, a load was not applied properly to the central portion, the portion excluding the four corners of the outer periphery, and the gasket, and the power generation performance was deteriorated and the seal was defective.

  The broken line parts PR1 and PR2 in FIG. 6 are parts to which a load is to be applied in the fuel cell stack 200. However, in this embodiment, a load can be applied appropriately, and no sealing failure occurs. On the other hand, in the reference example, since no load is applied to the center side, it is not possible to apply an appropriate load to the center side portion PR2 and the portion PR1 which is the outer peripheral portion that is not the four corners, resulting in a decrease in power generation performance. And a seal failure occurred.

D. Variation:
As mentioned above, although several embodiment of this invention was described, this invention is not limited to such embodiment at all, and implementation in various aspects is possible within the range which does not deviate from the summary. It is. For example, the following modifications are possible.

・ Modification 1:
In the above embodiment, the adhesive layer 50 is interposed between the separators 20 and 30 and the thin portion 44 of the resin frame 40 without being heated and pressed, but instead, the adhesive layer 50 is interposed. The thin-walled portion 44 may be configured such that no adhesive layer is interposed therebetween. Also in this case, the separators 20 and 30 and the thin portion 44 are in close contact with each other. With this configuration, the same effects as those of the above embodiment can be obtained. Further, the flat portion 42 and the thin portion 44 may be configured such that no adhesive layer is interposed therebetween. In this case, the material of the resin frame 40 may be adjusted so that at least a part thereof has adhesiveness.

Modification 2
In the above-described embodiment, when the fuel battery cell 100 is manufactured, the resin frame 40 including the flat part 42 and the thin part 44 is prepared, and the flat part is also obtained in the fuel battery cell manufactured through the heating press process. However, instead of this, when the fuel cell 100 is manufactured, the resin frame 40 including the flat portion 42 and the thin portion 44 is prepared. In the fuel cell after being manufactured through the hot press process, the fuel cell may be manufactured such that the difference in thickness between the flat portion 42 and the thin portion 44 becomes 0. That is, in the fuel cell after being manufactured through the hot press process, if the difference in thickness between the flat portion 42 and the thin portion 44 is 0 or more, each thickness t1 of the flat portion 42 and the thin portion 44 is obtained. , T2 may be any value.

・ Modification 3:
In the above embodiment, the recess 40a (FIG. 1) is formed in the resin frame 40 at the portion corresponding to the lower side of the gasket 60. On the other hand, as shown in FIG. 8, in the fuel cell 100X of Modification 3, the portion corresponding to the lower side of the gasket 60 in the resin frame 40X is flat, that is, has no recess. Even with the configuration of the third modification, it is possible to achieve the same effect as that of the first embodiment.

-Modification 4:
In the above embodiment, the thin-walled portion 44 is the four corners in the XY plane direction of the resin frame 40. However, instead of this, it may be a predetermined range including the middle part of each side connecting the corners. In short, any range can be used as long as it is a predetermined range including at least a part of the outer periphery of the resin frame in the XY plane direction. In this case, the hot press machine has a configuration in which a portion corresponding to the thin film portion is cut.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Moreover, elements other than the elements described in the independent claims among the constituent elements in the above-described embodiments and modifications are additional elements and can be omitted as appropriate.

10 ... Membrane electrode gas diffusion layer assembly (MEGA)
DESCRIPTION OF SYMBOLS 12 ... Electrolyte membrane 14 ... Catalyst electrode layer 15 ... Anode side gas diffusion layer 16 ... Catalyst electrode layer 17 ... Cathode side gas diffusion layer 20 ... Separator 22 ... Fuel gas flow path 30 ... Separator 32 ... Oxidant gas flow path 40 ... Resin Frame 42 ... Flat part 44 ... Thin part 50, 52 ... Adhesive layer 60 ... Gasket 71, 73, 75, 78 ... Through hole 80 ... Transport gripping part 90 ... Laminate 94 ... Resin frame 100 ... Fuel cell 200 ... Fuel Battery stack W ... Predetermined range HA ... Multi-finger hand part HP ... Heating press machine HP1 ... Heating press lower plate HP2 ... Heating press upper plate

Claims (1)

A method for producing a fuel cell, comprising:
A step of preparing a membrane electrode assembly and a power generator having a pair of gas diffusion layers disposed on both surfaces of the membrane electrode assembly, a separator, and a resin frame;
Disposing the resin frame on the outer periphery of the power generation body in a planar direction along the surface of the power generation body, and disposing the separator on the surfaces of the power generation body and the resin frame;
A step of gripping and transporting the arranged power generator, the resin frame, and the separator while holding a predetermined portion;
Pressing the power generator, the resin frame, and the separator in the gripped state except for the predetermined portion to be gripped; and
With
When preparing the resin frame, prepare a resin frame in which a portion corresponding to the predetermined portion to be gripped is thinner than the other portions, the thin portion is in close contact with the separator, and the thickness of the thin portion These are the manufacturing methods of a fuel cell smaller than the thickness of the other said pressed part.

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